Evaluation of the effects of 20% mannitol and 3% hypertonic saline usage in supratentorial tumor surgery on brain relaxation, hemodynamic parameters, PPV, PVİZ index, serum osmolarity, and electrolytes

Objective: Brain relaxation is of paramount importance in supratentorial tumor surgery, for which Mannitol is one of the most frequently used agents. Hypertonic Saline (HS) is also administered to reduce brain tension. In our study, we aimed to evaluate the effects of iso-osmolar 20% Mannitol and 3% HS applied during supratentorial tumor surgery on brain relaxation, hemodynamic parameters, urinary output and fluid balance, PPV, PVI, serum osmolarity, and electrolytes. Material and Method: A total of 60 patients between the ages of 18 and 65, classified as ASA 1-2, scheduled for supratentorial tumor surgery were included in the study. Anesthesia was maintained with sevoflurane and remifentanil to maintain an entropy level between 40-60. Mean arterial blood pressure (MAP) was targeted to be within 65-95 mmHg, and end-tidal CO2 (ETCO2) around 30-35 mmHg. After the patients were placed in their final position, they were divided into two groups: Group 1 received 20% Mannitol (2.5 ml/kg), and Group 2 received 3% Hypertonic Saline (2.5 ml/kg). Brain relaxation scores were assessed after dural opening.In the preoperative period, during anesthesia induction and after intubation, hemodynamic variables, blood gases, and Pleth Variability Index (PVI) were recorded. It was planned for the Pulse Pressure Variation (PPV) and PVI values to be ≤13%. Sodium and potassium levels, urine output, and fluid administered were recorded at 60 minutes, 2 hours, and 3 hours after the end of the infusion. Preoperative and postoperative blood urea nitrogen (BUN), creatinine, and osmolarity values were noted. Results: There were no differences in demographic characteristics. It was determined that brain relaxation scores were similar at the time of dural opening, as well as at the 2nd and 3rd hours. No differences were found in hemodynamic data. From the start of the infusion, PVI and PPV values were observed to be higher in the HS group compared to the Mannitol group. In the Mannitol group, urine output and fluid administration were higher. A decrease in sodium levels with Mannitol and an increase with HS were observed. BUN and creatinine values were similar, and serum osmolarity remained unchanged in the Mannitol group during the postoperative period, while it increased in the HS group. The mean durations of intensive care unit stay and hospital stay were similar. Conclusion: It was concluded that effective brain relaxation can be achieved with Mannitol and Hypertonic Saline (HS) in supratentorial tumor surgery without affecting hemodynamic changes. In the Mannitol group, concomitant fluid administration with diuresis led to a decrease in PPV and PVI values. There were no significant alterations in blood gases, serum sodium and potassium levels, BUN, creatinine, or osmolarity levels. Therefore, it was concluded that HS could be used as an alternative to Mannitol in supratentorial surgery.